Abstract: Heart rate variability (HRV) reflects the autonomic nervous system (ANS) activity and HRV parameters are extracted from electrocardiogram (ECG) signal. However, the conventional ECG electrodes such as Ag/AgCl electrode make a person uncomfortable due to electrolytic paste or conductive adhesive used for ensuring good contact between electrode and skin. In this study, the portable device with capacitive electrodes was designed to monitor ANS activity through clothes. By using capacitive electrodes, ECG can be measured without direct skin-contact through capacitive coupling between the body and the electrodes. To evaluate the possibility that the ANS activity can be monitored using the capacitive electrode system, HRV parameters extracted from the capacitive electrodes were compared with HRV parameters extracted from Ag/AgCl electrodes. Results showed that there was no significant difference between the HRV parameters of two different electrodes.